1. Field of the Invention
The present invention is directed to a pipe bend or elbow to be used in slurry pipelines. More particularly, the present invention is directed to a pipe bend or elbow which is highly resistant to abrasion by solid particulate material transported in slurry pipelines and the like.
2. Brief Description of the Prior Art
Slurry transporting pipelines or conduits have been used in the mining, energy, chemical and related industries for a long time. Such pipelines or conduits, often incorporate pipe bends or elbows, which are necessary to join straight pipe sections to one another at various angles.
Pipe bends or elbows, however, present special wear and abrasion problems precisely because they change the direction of the flow in the slurry pipeline. As is well known, when a moving fluid carrying suspended solid particles, is forced to turn in a pipe bend or elbow, the direction of the fluid flow is changed more readily than the direction of movement of the suspended solid particles.
Thus, whereas the fluid turns readily and follows the curve or bend, the suspended solid particulates, by virtue of their much greater inertia, tend to continue to travel on their original straight line trajectory. Therefore, the solid particulates tend to impinge on the wall of the pipe bend or elbow in the exterior of the turn to which the slurry flow is subjected in the elbow. The continuous impingement of the elbows of a slurry pipeline causes abrasion, and increased corrosion so that the elbows require frequent replacement or repair.
In an effort to overcome the above-noted problem, the prior art has devised certain improved bends or elbows for slurry transporting pipes and pipelines which have increased resistance to abrasion. U.S. Pat. Nos. 4,130,300; 1,518,705; 1,211,784; 2,350,759; and 3,794,359; 4,117,201; and 4,251,170 disclose such pipe bends or elbows of improved wear and abrasion resistance.
A common feature of the prior art pipe bends of improved-wear and abrasion resistance, as exemplified in the above-noted patents, is that a wear resistant liner is incorporated into the wear-prone area of the bend or elbow. The devices disclosed in the above-noted patents differ from one another principally in the material of the liners, and in the manner of affixing the liners to the pipe bend or elbow.
U.S. Pat. No. 2,350,759 discloses a still different type of pipe bend or elbow of improved wear resistance. In this device, a resinous material is introduced into the interior surface of the elbow in the area where impingement by solid particles is most likely. The solid particles are said in the patent to adhere to the resinous material and thereby form a self-renewing layer which protects the elbow from abrasion.
Disadvantages of the above-summarized prior art structures include the relatively high cost of incorporating a separate liner into the pipe bend or elbow. In addition, the wear and the abrasion resistance provided by the prior art structures is still, often less than desirable. The present invention provides a pipe bend or elbow of increased wear and abrasion resistance which overcomes many problems of the prior art, particularly the costs associated with assembling liners into the pipe bends.